The present invention relates generally to a display system for a vehicle, which displays an information image on or adjacent a front windshield, so that a vehicle driver can see necessary information without looking down to the ordinary instrument panel display. More specifically, the invention relates to a vehicular display system which utilizes the front windshield as a display screen and which selects a suitable section of the front windshield onto which to project display images.
Usually, vehicular speedometers, odometers, trip meters, fuel gauges, clocks and other necessary indicators for vehicle driving are mounted on an instrument panel located beneath the front windshield. When a vehicle driver is watching in front of the vehicle while driving, at least some of the indicators on the instrument panel lie outside of the driver's field of view. This requires that the driver look down at the instrument panel to see the indicators in order to obtain necessary driving information. This conventional arrangement thus requires extra effort on the part of the driver and tends to fatigue the vehicle driver's eyes. Additionally and more importantly, this conventional arrangement prevents the driver from seeing the indicators under certain vehicle running conditions under which intense observation of the forward field is required.
To ameliorate this problem, a so-called "heads-up" type vehicular display system has been proposed which forms images of necessary indicators on a predetermined section on the front windshield. However, conventional heads-up type display systems have not been at all successful since it has been difficult to move the display on the windshield to differing eye points according to the drivers'sitting positions and heights.
Conventionally proposed heads-up type display systems employ a lens and a reflector to form images on the front windshield. Since the front end of the vehicle compartment is very crowded with various accessories such as air conditioning, audio and so forth, the space available in the instrument panel for the display system is severely limited. As will be appreciated, the size of the display images on the windshield is determined by the dimensions of the lens and the reflector. Therefore, although a relatively small lens and reflector could be accommodated within the instrument panel, the size of the image would not suit all drivers, who tend to have varying eye elevations and postures, referred to hereafter as "eye points".
On the other hand, it has been found that if an appropriate section of the front windshield can be selected for each specific eye point, a clear display image can be achieved even if the image is not as large. Therefore, properly selecting the display section of the front windshield according to eye points, a clear and adequate display of the vehicle driving information can be provided on the front windshield.